Sheet feeding device

Abstract

A sheet feeding device includes a stacking plate, a pick-up device, means for blowing air, and a holding member. On the plate, sheets to be fed into a processing apparatus are placed. The device sends out a top one of the sheets placed on the plate, and has a pick-up roller to be brought into contact with an upper side of the top sheet at a position within a predetermined level range when the sheet is to be fed into the apparatus. The means blows air to the sheet with a predetermined force in a direction to separate the sheet from the other sheets placed on the plate or from the plate. The member is to be brought into contact with the upper side at a position upstream of the roller with respect to a feeding direction in which the sheet is to be fed into the apparatus.

1 . A sheet feeding device adapted for connection to a processing apparatus that performs predetermined processing on a sheet, the sheet feeding device comprising:
 a stacking plate for placing thereon sheets to be fed into the processing apparatus;   a pick-up device for sending out a top one of the sheets placed on the stacking plate, the pick-up device having a pick-up roller to be brought into contact with an upper side of the top sheet at a position within a predetermined level range when the top sheet is to be fed into the processing apparatus;   means for blowing air to the top sheet, when the top sheet is to be fed into the processing apparatus, with a predetermined force in a direction to separate the top sheet from the rest of the sheets placed on the stacking plate or from the stacking plate; and   a holding member adapted to be brought into contact with the upper side of the top sheet, when the top sheet is to be fed into the processing apparatus, at a position upstream of the pick-up roller with respect to a feeding direction in which the top sheet is to be fed into the processing apparatus.   
   
   
       2 . The sheet feeding device according to  claim 1 , further comprising a connecting member for connecting the holding member to a rotating shaft of the pick-up roller in such a manner that the holding member is pivotable within a predetermined range,
 wherein the pick-up device has a mechanism for moving the pick-up roller, up and down within a range that includes the predetermined level range, to bring the pick-up roller in and out of contact with the upper side of the top sheet.   
   
   
       3 . The sheet feeding device according to  claim 1 ,
 wherein:
 the stacking plate is adapted for sheets of a single size to be chosen from multiple sizes, to be placed thereon, and 
 the holding member is brought into contact with the upper side of the top sheet within an area of the stacking plate where a sheet of smallest size chosen from the multiple sizes is to be positioned. 
   
   
   
       4 . The sheet feeding device according to  claim 2 ,
 wherein:
 the pick-up device has a separating member for separating the top sheet from any other sheets sent out by the pick-up roller, at a separating position downstream of the pick-up roller with respect to the feeding direction, and 
 a distance between a position where the holding member is brought into contact with the upper side of the top sheet and a tail end of the top sheet along the feeding direction is set larger than a distance between the separating position and a leading end of the top sheet along the feeding direction. 
   
   
   
       5 . The sheet feeding device according to  claim 2 ,
 wherein:
 the stacking plate is adapted for sheets of a single size to be chosen from multiple sizes, to be placed thereon, 
 the pick-up device has a separating member for separating the top sheet from any other sheets simultaneously sent out by the pick-up roller, at a separating position downstream of the pick-up roller with respect to the feeding direction, and 
 a distance between a position where the holding member is to be brought into contact with an upper side of a top one of sheets, of smallest size chosen from the multiple sizes, placed on the stacking plate and a tail end of the top sheet along the feeding direction is set larger than a distance between the separating position and a leading end of the top sheet along the feeding direction. 
   
   
   
       6 . The sheet feeding device according to  claim 1 ,
 wherein the holding member has a curved surface to be brought into contact with the upper side of the top sheet.   
   
   
       7 . The sheet feeding device according to  claim 5 ,
 wherein the holding member has a cylindrical or spherical shape and is supported rotatably about a horizontal axis perpendicular to the feeding direction.